Beginner Exercise 170 / Solution

Sub-page of BeginnerExercise170
[Diagram]
Black lives (most likely)  

After B1, White has two options - the first is to allow a life for the top half and capture 10 stones in sente.

[Diagram]
White opts for ko  

The second is this ko for the whole group. But Black takes first and there would be no matching ko threats for such a huge ko (about 50 points worth) in most cases. So the above diagram is the most likely result.

(W2 at a is slightly better for points, but it gives Black a ko threat at W2 to live the top half)

[Diagram]
Probe (B3 to W6 elsewhere)  

(For advanced readers) In rare cases, B1 here may work as a probe. White must play W2 if he wants to kill the whole group. Then Black plays elsewhere to change the ko threat situation, and if successful plays B7 cut. Then B9 lives with two more points and destroys one point for White at a.



Beginner Exercise 170 / Solution last edited by hnishy on September 15, 2024 - 07:48
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